The present invention concerns an expansible mandrel in which loading and unloading of the member to be machined is effected while the mandrel is rotating.
The known installations make use of mandrels with slide members which are held in place by a resilient circular ring. The use of such mandrels makes it necessary to stop the machine whenever the machined member is to be removed and replaced on the mandrel by a fresh member to be machined.
Indeed, using such a known mandrel for machining members on permanently rotating machine tools is not to be recommended and is even dangerous. The return force of the resilient ring, by virtue of the effect of centrifugal force acting on the slide members, is insufficient to return the slide members to the release position. In addition, there is the danger of the ring breaking due to the effect of centrifugal force.
The aim of the present invention is to overcome this disadvantage and to provide a mandrel having a positive release system which comprises using centrifugal force to cause retraction of the slide members into apertures provided in the body of the mandrel, to permit ejection of the machined member and loading of the mandrel with a fresh member to be machined.